1. Field of the Invention
The present invention relates to a graphitizing electric furnace.
2. Discussion of the Background
Conventionally, artificial graphite powder has been industrially produced by graphitizing carbon powder through heat treatment under incrt atmosphere at temperature of about 3,000.degree. C. or more.
In the production of the graphite powder of this type, a graphitizing electric furnace such as an Acheson furnace has been used wherein carbon powder is graphitized by Joule's heat through direct supply of electric current to the carbon powder. Generally. existing graphitizing electric furnaces are designed to produce graphite powder in batch type production, resulting in low productivity. Therefore, there have been strong demands for development of a graphitizing electric furnace capable of continuously producing graphite powder by heat treatment of the carbon powder.
However, most of the continuous graphitizing electric furnaces as currently proposed are based on a design concept that carbon powder is charged into a space between a pair of graphite electrodes and electric current is supplied to the space while the carbon powder is moving, thereby heating the carbon powder by Joule's heat. The graphite electrodes themselves are also heated by Joule's heat to be positively utilized as heaters for maintaining the temperature inside the furnace to about 3,000.degree. C. or more so as to continuously graphitize the carbon powder, which will inevitably result in sublimation and wear of the graphite electrodes since they are exposed to temperature as high as about 3,000.degree. C. or more. Wear of the graphite electrodes has been and is a great obstacle to practical realization of continuous graphitizing electric furnaces.
To put it concretely, for example, a continuous graphitizing electric furnace is considered, in which a pair of graphite electrodes in the form of pipe is oppositely arranged in the furnace body, and a pair of which is to be as a carbon powder inlet and a graphite powder collecting port. In such a graphitizing electric furnace, when a carbon powder is charged in the furnace body and electric current is supplied to a space between pair of graphite electrodes from current source, the graphite electrodes themselves are heated to be functioned as heaters, the carbon powder, inside and at the center of the graphite electrodes, is graphitized to be heated by Joule's heat. Therefore, it has been thought that the graphite powder may be continuously produced by collecting the graphite powder through the one side of the graphite electrode pipe while new carbon powder is charged through the other side of it into the furnace body. Especially, it has been thought that the one side of the graphite elctrode pipe collecting the high-temperature graphite powder cannot bear to be used in long time since it is always disposed to high temperature and is easily sublimated.